Positional information display device, positional information display method, positional information display program, and radiography apparatus

ABSTRACT

A first positional information derivation unit derives three-dimensional positional information of at least one target point of a target structure in a subject as first positional information. A second positional information derivation unit derives three-dimensional positional information of at least one feature point on an insertion structure inserted to the target structure in the subject as second positional information. A display control unit displays a positional information screen indicating a positional relationship between the target point and the feature point on a display unit.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 toJapanese Patent Application No. 2019-060369 filed on Mar. 27, 2019. Theabove application is hereby expressly incorporated by reference, in itsentirety, into the present application.

BACKGROUND Technical Filed

The present disclosure relates to a positional information displaydevice, a positional information display method, a positionalinformation display program, and a radiography apparatus.

Related Art

In surgical operations and catheter treatments, it is necessary tounderstand the positional relationship between surgical instruments andhuman body structures such as bones and blood vessels. However, in therelated art, in many cases, the understanding of the positionalrelationship between a surgical instrument and a human body structuredepends on the experience and intuition of a doctor and there areproblems of an error in the insertion of the surgical instrument andexcessive surgery time. For this reason, a process is performed whichcaptures an image of a subject using a radioscopy apparatus duringsurgery and understands the positional relationship between a surgicalinstrument and a human body structure using a radioscopic imagedisplayed on a display by imaging. However, while a three-dimensionalpositional relationship is established between the surgical instrumentand the human body structure, the radioscopic image is a two-dimensionalimage. It is difficult for the user to understand the three-dimensionalpositional relationship between the surgical instrument and the humanbody structure even in a case in which the user views thetwo-dimensional radioscopic image.

For this reason, a process is performed which understands athree-dimensional positional relationship between a surgical instrumentand a human body structure, using radioscopic images in a plurality ofdirections acquired by capturing the images of a patient as a subjectwhile changing an angle during a medical procedure or by using aplurality of imaging apparatuses at the same time. In addition, a methodhas been proposed in which a sensor is attached to a surgical instrumentto understand the three-dimensional position of the surgical instrument.

However, in a case in which an image of a subject is captured while theangle is changed, it is necessary to move the imaging apparatus during amedical procedure. In addition, in a case in which a plurality ofimaging apparatuses are used at the same time, it is not necessary tomove the imaging apparatuses, but a work space for the doctor duringsurgery is reduced, which may hinder the procedure. Further, in themethod using a sensor, it is necessary to prepare a sensor.

For this reason, a method has been proposed which aligns athree-dimensional image that is formed by a plurality of tomographicimages acquired in advance by, for example, a computed tomography (CT)apparatus and a magnetic resonance imaging (MRI) apparatus and atwo-dimensional radiographic image obtained by capturing an image of aleading end of a catheter to synchronize the radiographic image with thetomographic image including the position of the leading end of thecatheter in the three-dimensional image and updates and displays theimages (see JP2013-066802A). According to the method described inJP2013-066802A, the doctor can check the position of the leading end ofthe catheter in the subject by viewing the tomographic image. Therefore,it is possible to easily perform a medical procedure.

In surgical operations and catheter treatments, it is necessary tounderstand the positional relationship between a surgical instrument anda human body structure in real time. However, in the method described inJP2013-066802A, the processing time for aligning the three-dimensionalimage and the radiographic image is required. In recent years, since theresolution and density resolution of radiographic images have improved,the amount of image data indicating a three-dimensional image and aradiographic image has become very large. Time is required for a processto align the three-dimensional image and the radiographic image having alarge amount of data. For this reason, in the method described inJP2013-066802A, it is difficult to understand the position between thesurgical instrument and the human body structure in the subject and thepositional relationship therebetween in real time.

SUMMARY OF THE INVENTION

The present disclosure has been made in view of the above-mentionedproblems and an object of the present disclosure is to provide atechnique that enables a user to understand a positional relationshipbetween a structure inserted into a subject, such as a surgicalinstrument, and a target structure in the subject in real time.

According to the present disclosure, there is provided a positionalinformation display device comprising: a first positional informationderivation unit that derives three-dimensional positional information ofat least one target point of a target structure in a subject as firstpositional information; a second positional information derivation unitthat derives three-dimensional positional information of at least onefeature point on an insertion structure inserted to the target structurein the subject as second positional information; and a display controlunit that displays a positional information screen indicating apositional relationship between the target point and the feature pointon a display unit.

The positional information display device according to the presentdisclosure may further comprise: an image acquisition unit that acquiresa radiographic image set including a plurality of radiographic images,which have been generated by alternately irradiating the subject withradiation emitted from a plurality of radiation sources provided atdifferent positions and alternately detecting the radiation transmittedthrough the subject using one detection unit, at a predetermined timeinterval; and a feature point detection unit that detects the featurepoint on the insertion structure in the subject from each of theplurality of radiographic images included in the radiographic image set.The second positional information derivation unit may derive the secondpositional information using a positional relationship between aposition of the feature point detected from each of the plurality ofradiographic images on a detection surface of the detection unit andpositions of the plurality of radiation sources.

The “predetermined time interval” means, for example, a time intervalcorresponding to the frame rate of a moving image. The predeterminedtime interval may be, for example, 25 to 60 fps. As a result, in thepresent disclosure, a combination of radiographic images, such as amoving image, is acquired. In addition, all of the plurality ofradiographic images may be acquired at the same time interval or theplurality of radiographic images may be acquired at different timeintervals.

In the positional information display device according to the presentdisclosure, the display control unit may display the positionalinformation screen including a radiographic image display region inwhich some of the plurality of radiographic images are displayed and apositional relationship display region in which the positionalrelationship is displayed on the display unit.

The term “some of the radiographic images” means radiographic imagesacquired on the basis of the transition of radiation emitted from one ofthe plurality of radiation sources.

The positional information display device according to the presentdisclosure may further comprise a notification unit that notifies thatthe feature point has reached the target point.

In the positional information display device according to the presentdisclosure, the notification unit may issue a warning in a case in whichthe feature point deviates from the target point by a predetermineddistance or angle.

In the positional information display device according to the presentdisclosure, the insertion structure may be a surgical instrument that isinserted into the subject.

In the positional information display device according to the presentdisclosure, the target structure may be a stent that is inserted into ablood vessel of the subject. The target point may be a center positionof an end portion of the stent. The insertion structure may be a guidewire for expanding the stent. The feature point may be a leading end ofthe guide wire.

In the positional information display device according to the presentdisclosure, the target structure may be a lumbar spine of the subject.The target point may be at least one of an insertion position or anarrival position of a screw that is inserted into the lumbar spine. Theinsertion structure may be the screw. The feature point may be at leastone of a leading end or a rear end of the screw.

According to the present disclosure, there is provided a radiographyapparatus comprising: a plurality of radiation sources that are providedat a predetermined interval; a detection unit that is provided so as toface the plurality of radiation sources, detects radiation which hasbeen emitted from each of the plurality of radiation sources andtransmitted through a subject, and generates a radiographic image of thesubject; an imaging control unit that generates a radiographic image setincluding a plurality of radiographic images at a predetermined timeinterval by controlling a time point when each of the plurality ofradiation sources emits the radiation and a time point when thedetection unit detects the radiation transmitted through the subjectsuch that the plurality of radiation sources alternately irradiate thesubject with the radiation and the detection unit alternately detectsthe radiation transmitted through the subject; and the positionalinformation display device according to the present disclosure.

In the radiography apparatus according to the present disclosure, thenumber of radiation sources may be 2.

In the radiography apparatus according to the present disclosure, theimaging control unit may direct one of the two radiation sources tosequentially emit radiation at a first time interval, direct the otherradiation source to sequentially emit radiation at a second timeinterval equal to or longer than the first time interval, and controlthe detection unit so as to detect the radiation at all time points whenthe two radiation sources emit the radiation. The image acquisition unitmay acquire, as the radiographic image set, two radiographic imagesgenerated by detecting two temporally adjacent radiations which havebeen emitted from the two radiation sources using the detection unit.

The term “being equal to or longer than the first time interval” meansbeing equal to the first time interval and being longer than the firsttime interval.

According to the present disclosure, there is provided a positionalinformation display method comprising: deriving three-dimensionalpositional information of at least one target point of a targetstructure in a subject as first positional information; derivingthree-dimensional positional information of at least one feature pointon an insertion structure inserted to the target structure in thesubject as second positional information; and displaying a positionalinformation screen indicating a positional relationship between thetarget point and the feature point on a display unit.

In addition, a program that causes a computer to perform the positionalinformation display method according to the present disclosure may beprovided.

According to the present disclosure, there is provided anotherpositional information display device comprising a memory that storescommands to be executed by a computer and a processor that is configuredto execute the stored commands. The processor performs a process ofderiving three-dimensional positional information of at least one targetpoint of a target structure in a subject as first positionalinformation, a process of deriving three-dimensional positionalinformation of at least one feature point on an insertion structureinserted to the target structure in the subject as second positionalinformation, and a process of displaying a positional information screenindicating a positional relationship between the target point and thefeature point on a display unit.

According to the present disclosure, it is possible to understand thepositional relationship between the target structure and the insertionstructure in the subject in real time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically illustrating the configuration of aradiography apparatus to which a positional information display deviceaccording to an embodiment of the present disclosure is applied.

FIG. 2 is a diagram schematically illustrating the configuration of aradiation emitting unit.

FIG. 3 is a diagram schematically illustrating the configuration of thepositional information display device implemented by installing apositional information display program in a computer in this embodiment.

FIG. 4 is a diagram illustrating the time point when first and secondradiation sources emit radiation and the time point when a radiationdetector detects radiation.

FIG. 5 is a diagram illustrating a radioscopic image displayed in a casein which a catheter treatment is performed.

FIG. 6 is a diagram illustrating a state in which there is a differencebetween the positions of a stent and a guide wire.

FIG. 7 is a diagram illustrating lumbar spine fusion.

FIG. 8 is a diagram illustrating the derivation of three-dimensionalpositional information of a feature point.

FIG. 9 is a diagram illustrating imaging in two directions.

FIG. 10 is a diagram illustrating radiographic images acquired byimaging in two directions.

FIG. 11 is a diagram illustrating projection images in two directionsgenerated from a three-dimensional image.

FIG. 12 is a diagram illustrating radiographic images acquired byimaging in two directions.

FIG. 13 is a diagram illustrating a positional information screen in thecase of a catheter treatment.

FIG. 14 is a diagram illustrating a positional information screen in thecase of lumbar spine fusion.

FIG. 15 is a flowchart illustrating a process performed in thisembodiment.

FIG. 16 is a diagram illustrating the time point when the first andsecond radiation sources emit radiation and the time point when theradiation detector detects radiation.

DETAILED DESCRIPTION

Hereinafter, an embodiment of the present disclosure will be describedwith reference to the drawings. FIG. 1 is a diagram schematicallyillustrating the configuration of a radiography apparatus to which apositional information display device according to the embodiment of thepresent disclosure is applied. The radiography apparatus according tothis embodiment acquires and displays a radioscopic image of a subject Has a moving image in a case in which, for example, a surgical operationand a catheter treatment are performed on the subject H.

In this embodiment, it is assumed that the x-axis is set as theleft-right direction of FIG. 1 , the y-axis is set as the depthdirection of FIG. 1 , and the z-axis is set as a direction perpendicularto the plane on which the radiography apparatus 1 illustrated in FIG. 1is placed.

As illustrated in FIG. 1 , the radiography apparatus 1 according to thisembodiment comprises a C-arm 2. An imaging unit 3 is attached to one endportion of the C-arm 2 and a radiation emitting unit 4 is attached tothe other end portion so as to face the imaging unit 3.

A radiation detector 5, such as a flat panel detector, is provided inthe imaging unit 3. The radiation detector 5 corresponds to a detectionunit according to the present disclosure. In addition, for example, acircuit substrate provided with a charge amplifier that converts acharge signal read from the radiation detector 5 into a voltage signal,a correlated double sampling circuit that samples the voltage signaloutput from the charge amplifier, an analog-to-digital (AD) conversionunit that converts the voltage signal into a digital signal, and thelike is provided in the imaging unit 3. In this embodiment, theradiation detector 5 is used. However, the detector is not limited tothe radiation detector 5 as long as it can detect radiation and convertthe radiation into an image. For example, a detection device, such as animage intensifier, may be used.

The radiation detector 5 can repeatedly perform the recording andreading of a radiographic image and may be a so-called direct-typeradiation detector that directly converts radiation, such as X-rays,into charge or a so-called indirect-type radiation detector thatconverts radiation into visible light and then converts the visiblelight into a charge signal. In addition, it is preferable that aso-called TFT reading method which turns on and off a thin filmtransistor (TFT) switch to read a radiographic image signal or aso-called optical reading method which emits reading light to read aradiographic image signal is used as a radiographic image signal readingmethod. However, the invention is not limited thereto and other readingmethods may be used.

FIG. 2 is a diagram schematically illustrating the configuration of theradiation emitting unit 4. As illustrated in FIG. 2 , a first radiationsource 6A and a second radiation source 6B are provided in the radiationemitting unit 4. The first and second radiation sources 6A and 6B arearranged side by side at a predetermined interval in the depth direction(that is, the y-axis direction) of FIG. 1 . First and second radiationsR1 and R2 emitted from the first and second radiation sources 6A and 6Bare emitted to the imaging unit 3 through first and second emissionportions 4A and 4B, respectively.

The first and second radiation sources 6A and 6B emit X-rays asradiation and an imaging control unit 14 which will be described belowcontrols the time point when the first and second radiation sources 6Aand 6B emit radiation and the time point when the radiation detector 5detects the first and second radiations R1 and R2. In addition, forexample, the imaging control unit 14 controls the radiation generationconditions of the first and second radiation sources 6A and 6B, that is,the selection of a target and a filter material, a tube voltage, and anirradiation time.

In the radiography apparatus 1 according to this embodiment, a so-calledsource image distance (SID) which is a distance between a detectionsurface 5A of the radiation detector 5 and the first and secondradiation sources 6A and 6B of the radiation emitting unit 4 is a fixedvalue.

The C-arm 2 according to this embodiment is held by a C-arm holdingportion 7 such that the C-arm 2 can be moved in the direction of anarrow A illustrated in FIG. 1 and the angle of the imaging unit 3 andthe radiation emitting unit 4 with respect to the z direction (verticaldirection) illustrated in FIG. 1 can be integrally changed. Further, theC-arm holding portion 7 has a shaft portion 8 and the shaft portion 8connects the C-arm 2 to a bearing 9 so as to be rotatable. Therefore,the C-arm 2 is rotatable on the shaft portion 8 as a rotation axis inthe direction of an arrow B illustrated in FIG. 1 .

In addition, as illustrated in FIG. 1 , the radiography apparatus 1according to this embodiment comprises a main body unit 10. The mainbody unit 10 has a plurality of wheels 11 attached to the bottom.Therefore, the radiography apparatus 1 according to this embodiment canbe moved. A support shaft 12 that expands and contracts in the z-axisdirection of FIG. 1 is provided in an upper part of a housing of themain body unit 10 in FIG. 1 . The bearing 9 is held above the supportshaft 12 so as to be movable in the direction of an arrow C.

Since the radiography apparatus 1 according to this embodiment has theabove-mentioned configuration, the subject H who lies in a supineposition on the imaging table 40 is irradiated with radiation from thelower side of the subject H and the radiation detector 5 of the imagingunit 3 detects the radiation transmitted through the subject H toacquire a radiographic image of the subject H. Here, the C-arm 2 ismovable in the direction of the arrow A, the direction of the arrow B,and the direction of the arrow C and the radiography apparatus 1 ismovable by the wheels 11. Therefore, the radiography apparatus 1according to this embodiment can capture an image of a desired part ofthe subject H who lies in a supine position on the imaging table 40 in adesired direction.

The main body unit 10 is provided with an interface (I/F) unit 13, theimaging control unit 14, and a positional information display device 15according to this embodiment.

The I/F unit 13 has a function of performing wireless or wiredcommunication with an external apparatus and a console that controls theoverall operation related to the capture of a radiographic image by theradiography apparatus 1 (which are not illustrated). The radiographyapparatus 1 according to this embodiment captures an image of thesubject H on the basis of an imaging command received from the consolethrough the I/F unit 13.

The imaging control unit 14 directs the first and second radiationsources 6A and 6B of the radiation emitting unit 4 to emit the first andsecond radiations R1 and R2 on the basis of the imaging conditionsassociated with an imaging command from the console, respectively. Inaddition, the imaging control unit 14 directs the radiation detector 5of the imaging unit 3 to detect the first and second radiations R1 andR2 transmitted through the subject H according to the time point whenthe first and second radiations R1 and R2 are emitted from the first andsecond radiation sources 6A and 6B, respectively, and generates firstand second radiographic images G1 and G2 of the subject H. The generatedfirst and second radiographic images G1 and G2 are output to the mainbody unit 10. The time point when the first and second radiations R1 andR2 are emitted from the first and second radiation sources 6A and 6B,respectively, and the time point when the radiation detector 5 detectsthe first and second radiations R1 and R2 will be described below.

In addition, a user interface 16 is provided above the main body unit10. The user interface 16 has a function by which a user, such as atechnician or a doctor who takes a radiographic image using theradiography apparatus 1, inputs a command related to the capture of aradiographic image, a function which displays a radiographic imageacquired by imaging as a radioscopic image, and a function whichprovides information related to the capture of a radiographic image tothe user. A touch panel display is given an example of the userinterface 16.

Next, the positional information display device according to thisembodiment will be described. FIG. 3 is a diagram schematicallyillustrating the configuration of the positional information displaydevice according to this embodiment. As illustrated in FIG. 3 , thepositional information display device 15 is a computer and comprises acentral processing unit (CPU) 21, a memory 22, and a storage 23 as theconfiguration of a standard computer.

A positional information display program according to this embodiment isinstalled in the positional information display device 15 according tothis embodiment. The positional information display program is stored ina storage device of a server computer connected to the network or anetwork storage such that it can be accessed from the outside, isdownloaded to the positional information display device 15 through theI/F unit 13 on demand, and is installed in the positional informationdisplay device 15. Alternatively, the positional information displayprogram is recorded on a recording medium, such as a digital versatiledisc (DVD) or a compact disc read only memory (CD-ROM), is distributed,and is installed in the positional information display device 15 fromthe recording medium.

The storage 23 is a storage device, such as a hard disk drive or a solidstate drive (SSD), and stores various kinds of information including thepositional information display program. The radiographic image acquiredby imaging is also stored in the storage 23.

For example, the programs stored in the storage 23 are temporarilystored in the memory 22 in order to cause the CPU 21 to perform variousprocesses. The positional information display program defines, asprocesses performed by the CPU 21, a first positional informationderivation process that derives three-dimensional positional informationof at least one target point of a target structure in the subject H asfirst positional information, an image acquisition process that acquiresa radiographic image set including the first and second radiographicimages G1 and G2 acquired by the radiography apparatus 1 at apredetermined time interval, a feature point detection process thatdetects at least one common feature point on an insertion structureinserted into the target structure in the subject H from each of thefirst and second radiographic images G1 and G2 included in theradiographic image set, a second positional information derivationprocess that derives three-dimensional positional information of atleast one feature point in the subject H as second positionalinformation, using a positional relationship between the position of thefeature point detected from the first and second radiographic images G1and G2 on the detection surface 5A of the radiation detector 5 and thepositions of the first and second radiation sources 6A and 6B, a displaycontrol process that displays a positional information screen indicatinga positional relationship between the target point and the feature pointon the user interface 16, and a notification process that notifies thatthe feature point has reached the target point.

Then, the CPU 21 performs these processes according to the positionalinformation display program such that the computer functions as thepositional information display device 15 comprising a first positionalinformation derivation unit 30, an image acquisition unit 31, a featurepoint detection unit 32, a second positional information derivation unit33, a display control unit 34, and a notification unit 35.

The first positional information derivation unit 30 derives thethree-dimensional positional information of at least one target point ofthe target structure in the subject H as the first positionalinformation. The first positional information derivation unit 30 will bedescribed below.

The image acquisition unit 31 acquires a radiographic image setincluding the first and second radiographic images G1 and G2 of thesubject H generated by the control of the imaging control unit 14 forthe first and second radiation sources 6A and 6B and the radiationdetector 5. Next, the time point when the first and second radiationsources 6A and 6B emit the first and second radiations R1 and R2 and thetime point when the radiation detector 5 detects the first and secondradiations R1 and R2 will be described. FIG. 4 is a diagram illustratingthe time point when the first and second radiation sources 6A and 6Bemit the first and second radiations R1 and R2 and the time point whenthe radiation detector 5 detects the first and second radiations R1 andR2.

FIG. 4 illustrates a time point T1 when the first radiation source 6Aemits the first radiation R1, a time point T2 when the second radiationsource 6B emits the second radiation R2, and a time point T3 when theradiation detector 5 detects the first and second radiations R1 and R2.In addition, T4 is a second positional information derivation time pointwhich will be described below.

As illustrated in FIG. 4 , in a case in which the first radiation R1 isemitted from the first radiation source 6A, the radiation detector 5detects the first radiation R1 transmitted through the subject H andgenerates the first radiographic image G1. In a case in which theradiation detector 5 generates the first radiographic image G1, thesecond radiation source 6B emits the second radiation R2 and theradiation detector 5 detects the second radiation R2 transmitted throughthe subject H and generates the second radiographic image G2. In a casein which the radiation detector 5 generates the second radiographicimage G2, the first radiation source 6A emits the next first radiationR1 and the radiation detector 5 detects the next first radiation R1transmitted through the subject H and generates the next firstradiographic image G1. This is repeated to alternately and repeatedlyacquire the first radiographic image G1 and the second radiographicimage G2. The image acquisition unit 31 acquires the first and secondradiographic images G1 and G2 that are temporally adjacent to each otheras the radiographic image set.

The time interval at which the radiation detector 5 generates the firstand second radiographic images G1 and G2 is 25 to 60 fps, for example,30 fps. In a case in which the time interval at which the first andsecond radiographic images G1 and G2 are generated is 30 fps, the timepoint when the first and second radiations R1 and R2 are emitted fromthe first and second radiation sources 6A and 6B, respectively, is 15fps.

Here, a medical procedure in a case in which a catheter treatment isperformed for the abdominal aneurysm of the subject H using theradiography apparatus 1 according to this embodiment will be described.FIG. 5 is a diagram illustrating a radioscopic image displayed on theuser interface 16 in a case in which a catheter treatment is performed.As illustrated in FIG. 5 , in a case in which a catheter treatment forthe abdominal aneurysm is performed, a bifurcated stent 51 inserted intoa guide wire 52 is inserted into the aorta 50 from the artery in onegroin and one branch 51A of the stent 51 is expanded by the guide wire52. Then, an operation is performed which inserts another guide wire 53into the aorta 50 from the artery in the other groin and passes theguide wire 53 through the other branch 51B of the stent 51 to expand thebranch 51B of the stent 51. In this case, in this embodiment, the firstradiographic image G1 or the second radiographic image G2 of theabdominal aneurysm of the subject H is displayed as a radioscopic imageof the moving image on the user interface 16. The user performs anoperation of passing the guide wire 53 through the branch 51B of thestent 51 while viewing the radioscopic image displayed on the userinterface 16.

Here, the diameter of the branch 51B of the stent 51 is small and theradioscopic image displayed on the user interface 16 is atwo-dimensional image. Therefore, it is difficult to know athree-dimensional positional relationship between an end portion of thebranch 51B of the stent 51 and a leading end 53A of the guide wire 53.For example, in the radioscopic image illustrated in FIG. 5 , the guidewire 53 seems to be inserted into the branch 51B of the stent 51.However, in practice, as illustrated in FIG. 6 , there is a possibilitythat the guide wire 53 will not be inserted into the branch 51B.

Further, in a case in which lumbar spine fusion is performed, aradiographic image of the front of the subject H is captured, a screwinsertion position is determined, a radioscopic image of the side of thesubject H illustrated in FIG. 7 is displayed as a moving image, and ascrew 55 is inserted into the lumbar spine 56 while a depth and an angleare checked. However, since the radioscopic image is a two-dimensionalimage, it is difficult to know the insertion position and insertionangle of the screw 55 and erroneous insertion is likely to occur. Thisembodiment has been made in order to solve these problems.

The feature point detection unit 32 detects at least one common featurepoint in the subject H from each of the first and second radiographicimages G1 and G2 included in the radiographic image set. For example, inthe case of the catheter treatment, the leading end 53A of the guidewire 53 included in each of the first and second radiographic images G1and G2 is detected as the feature point. The guide wire 53 is aninsertion structure according to the present disclosure. In the case ofthe lumbar spine fusion, a leading end 55A and a rear end 55B of thescrew 55 included in each of the first and second radiographic images G1and G2 are detected as the feature points. The screw 55 is the insertionstructure according to the present disclosure. In this embodiment, thefeature point detection unit 32 has a learned model which has beentrained so as to detect the feature points in the first and secondradiographic images G1 and G2.

The feature point includes not only one pixel but also a region having acertain area formed by a plurality of pixels. For example, the leadingend 53A of the guide wire 53, the leading end 55A of the screw 55, andthe rear end 55B of the screw 55 have a certain area and are included inthe feature points in this embodiment.

The learned model is a neural network that has been subjected todeep-learning so as to detect the feature points included in the firstand second radiographic images G1 and G2. The learned model is generatedby training a neural network using a large number of images, in whichfeature points have been known, as training data. Therefore, in a casein which the first and second radiographic images G1 and G2 are input,the feature point detection unit 32 detects a common feature point fromthe first and second radiographic images G1 and G2 and outputs thetwo-dimensional position coordinates of the detected feature point.

The learned model may be, for example, a support vector machine (SVM), aconvolutional neural network (CNN), and a recurrent neural network (RNN)in addition to the neural network subjected to deep learning.

In this embodiment, the feature point detection unit 32 detects thefeature points using the learned model. However, the invention is notlimited thereto. For example, any method, such as a method for detectingthe feature points included in the first and second radiographic imagesG1 and G2 using template matching, may be used as a method for detectingthe feature points.

The second positional information derivation unit 33 derives thethree-dimensional positional information of the feature point in thesubject H as second positional information, using the positionalrelationship between the position of the feature point detected from thefirst and second radiographic images G1 and G2 on the detection surface5A of the radiation detector 5 and the positions of the first and secondradiation sources 6A and 6B. FIG. 8 is a diagram illustrating thederivation of the three-dimensional positional information of thefeature point. The second positional information derivation unit 33acquires the information of a radiation source position S1 (sx1, sy1,sz1) of the first radiation source 6A, a radiation source position S2(sx2, sy2, sz2) of the second radiation source 6B, a position D1 (dx1,dy1, dz1) of the feature point detected in the first radiographic imageG1, and a position D2 (dx2, dy2, dz2) of the feature point detected inthe second radiographic image G2 illustrated in FIG. 8 .

In a case in which a coordinate system having, as the origin, anyposition on the C-arm 2 of the radiography apparatus 1 is set, thethree-dimensional coordinates (sx1, sy1, sz1) of the radiation sourceposition S1 and the three-dimensional coordinates (sx2, sy2, sz2) of theradiation source position S2 can be derived on the basis of thepositional relationship between the origin and the first and secondradiation sources 6A and 6B. For example, in this embodiment, acoordinate system having, as the origin, a point that bisects a lineconnecting the centers of the first and second emission portions 4A and4B of the radiation emitting unit 4 can be set.

Since the SID is known, it is possible to derive the three-dimensionalcoordinates of the center position of the detection surface 5A of theradiation detector 5 with respect to the origin. In addition, it ispossible to derive the three-dimensional coordinates of the positions D1and D2 of the feature point from the two-dimensional positioncoordinates of the feature point in the first and second radiographicimages G1 and G2 detected by the feature point detection unit 32, usingthe three-dimensional coordinates of the center position of thedetection surface 5A of the radiation detector 5.

The second positional information derivation unit 33 sets a straightline L1 connecting the radiation source position S1 and the position D1of the feature point and a straight line L2 connecting the radiationsource position S2 and the position D2 of the feature point. Any pointP1 on the straight line L1 and any point P2 on the straight line L2 areexpressed by the following Expression (1) using the radiation sourcepositions S1 and S2 and the positions D1 and D2 of the feature point. InExpression (1), t and s are parameters.P1=(1−t)·S1+t·D1P2=(1−s)·S2+s·D2  (1)

Ideally, the feature point in the subject H detected in the first andsecond radiographic images G1 and G2 is located at an intersection pointbetween the point P1 on the straight line L1 and the point P2 on thestraight line L2 in a three-dimensional space. Therefore, in thisembodiment, the second positional information derivation unit 33 derivesthe three-dimensional coordinates of a point, at which the distancebetween the point P1 and the point P2 is the minimum, as secondpositional information P0(x0, y0, z0) which is the three-dimensionalpositional information of the feature point detected in the first andsecond radiographic images G1 and G2, using the following Expression(2):P0=min(P1−P2)²  (2).

In a case in which the insertion structure is the guide wire 53, thesecond positional information derivation unit 33 derives thethree-dimensional coordinates of the leading end 53A of the guide wire53 as the second positional information. In a case in which theinsertion structure is the screw 55, the second positional informationderivation unit 33 derives the three-dimensional coordinates of theleading end 55A and the rear end 55B of the screw 55 as the secondpositional information.

In a case in which the image acquisition unit 31 acquires a radiographicimage set including the first and second radiographic images G1 and G2at successive time points, the second positional information derivationunit 33 derives the second positional information P0 using the first andsecond radiographic images G1 and G2 included in the acquiredradiographic image set. Therefore, the time point when the secondpositional information derivation unit 33 derives the second positionalinformation P0 is a time point T4 illustrated in FIG. 4 .

Next, the first positional information derivation unit 30 will bedescribed. The first positional information derivation unit 30 capturesthe images of the subject H in two directions and derives thethree-dimensional positional information of at least one target point ofa target structure, which is a target during a medical procedure, in thesubject H as the first positional information. For example, in the caseof a catheter treatment for the abdominal aneurysm, first, an operationis performed which expands the branch 51A after the stent 51 is insertedand inserts the guide wire 53 into the branch 51B. Therefore, the firstpositional information derivation unit 30 derives the three-dimensionalcoordinates of the center position of an end portion of the branch 51Bof the stent 51 as the first positional information. The stent 51 is thetarget structure according to the present disclosure and the centerposition of the end portion of the branch 51B of the stent 51 is thetarget point according to the present disclosure. The target pointincludes not only one pixel but also a region having a certain areaformed by a plurality of pixels. FIG. 9 is a diagram illustrating thecapture of the images of the subject H in two directions and FIG. 10 isa diagram illustrating radiographic images acquired by the imaging intwo directions.

The C-arm 2 is moved to the state illustrated in FIG. 1 and the imagingcontrol unit 14 irradiates the subject H with radiation in the directionof an arrow E1 illustrated in FIG. 9 to acquire a radiographic image GE1illustrated in FIG. 10 in response to a command from the user. Inaddition, the radiation emitting unit 4 is moved to the right side ofthe subject H in FIG. 1 and the subject H is irradiated with radiationin the direction of an arrow E2 to acquire a radiographic image GE2illustrated in FIG. 10 . The radiographic images GE1 and GE2 include theimage of the stent 51. The coordinates of the center positions of theradiographic images GE1 and GE2 are known since they are matched withthe coordinates of the center position of the detection surface 5A ofthe radiation detector 5. Therefore, the first positional informationderivation unit 30 derives the three-dimensional coordinates of thecenter position of the end portion of the branch 51B, into which theguide wire for the stent 51 is to be inserted, in the radiographicimages GE1 and GE2 as the first positional information which is thethree-dimensional positional information of the target point in the samecoordinate system as that in a case in which the feature point isdetected.

Here, the coordinate system is not limited to the same coordinate systemas that in a case in which the feature point is detected. For example, acoordinate system having the center position of the end portion of thebranch 51B of the stent 51 as the origin may be set.

In addition, the first positional information derivation unit 30 maydirect the radiography apparatus 1 to perform tomosynthesis imaging togenerate a three-dimensional image of a target part of the subject H andmay derive the first positional information from the three-dimensionalimage acquired by the tomosynthesis imaging.

In the tomosynthesis imaging, while the C-arm 2 is being rotated in thedirection of the arrow A, one (here, the first radiation source 6A) ofthe first and second radiation sources 6A and 6B emits radiation at aplurality of radiation source positions to capture the images of thesubject H, thereby acquiring a plurality of projection images. Then, thefirst positional information derivation unit 30 reconstructs theplurality of projection images using a back projection method, such as asimple back projection method or a filtered back projection method, togenerate tomographic images in a plurality of tomographic planes of thesubject H. Then, a three-dimensional image formed by the plurality oftomographic images is generated.

The first positional information derivation unit 30 performs coordinatetransform such that the coordinate system of the three-dimensional imageis matched with the coordinate system of the feature point and derivesthe three-dimensional coordinates of the center position of the endportion of the branch 51B of the stent 51 as the first positionalinformation. In this case, a coordinate system having the centerposition of the end portion of the branch 51B of the stent 51 as theorigin may be set.

In addition, the first positional information derivation unit 30 mayderive the first positional information from a three-dimensional imagewhich has been acquired in advance by, for example, a CT apparatus andan MRI apparatus. In this case, similarly to the three-dimensional imageacquired by the tomosynthesis imaging, the first positional informationderivation unit 30 may perform coordinate transform such that thecoordinate system of the three-dimensional image which has been acquiredin advance is matched with the coordinate system of the feature pointand may derive the three-dimensional coordinates of the center positionof the end portion of the branch 51B of the stent 51 as the firstpositional information. In this case, a coordinate system having thecenter position of the end portion of the branch 51B of the stent 51 asthe origin may be set.

In contrast, in a case in which lumbar spine fusion is performed, thefirst positional information derivation unit 30 derives, as the firstpositional information, the three-dimensional coordinates of aninsertion position and an arrival position in the lumbar spine whichhave been specified in advance in the three-dimensional image of thesubject H acquired by the CT apparatus or the MRI apparatus before amedical procedure. The lumbar spine is the target structure according tothe present disclosure and the insertion position and the arrivalposition are the target points according to the present disclosure. Inthis case, the first positional information derivation unit 30 generatesprojection images GP1 and GP2 obtained by projecting thethree-dimensional image in the direction of the arrow E1 and thedirection of the arrow E2 illustrated in FIG. 9 , respectively. FIG. 11is a diagram illustrating the projection images in two directions. Asillustrated in FIG. 11 , the projection image GP1 is a front view of thelumbar spine of the subject H and the projection image GP2 is a sideview of the lumbar spine of the subject H. Here, the insertion positionand the arrival position of the screw 55 are predetermined and set onthe three-dimensional image by an examination before a medicalprocedure. Therefore, an insertion position PS and an arrival positionPE are specified in the projection images GP1 and GP2.

In addition, the first positional information derivation unit 30captures the images of the subject H in the two directions illustratedin FIG. 9 and acquires radiographic images GE11 and GE12 illustrated inFIG. 12 . Then, the first positional information derivation unit 30matches the coordinate system of the radiographic images GE11 and GE12with the coordinate system of the projection images GP1 and GP2 andspecifies an insertion position PS1 and an arrival position PE1 in theradiographic images GE11 and GE12. In this case, it is preferable thatthe coordinate systems to be matched with each other have the insertionposition PS in the projection images GP1 and GP2 as the origin. However,the invention is not limited thereto. The coordinate system of theradiographic images GE11 and GE12 may be matched with a coordinatesystem having any point on the projection images GP1 and GP2 as theorigin or the coordinate system of the projection images GP1 and GP2 maybe matched with the coordinate system of the radiographic images GE11and GE12.

The display control unit 34 displays a positional information screenindicating the positional relationship between the target point and thefeature point on the user interface 16. FIG. 13 is a diagramillustrating a positional information screen in a case in which acatheter treatment is performed. As illustrated in FIG. 13 , apositional information screen 60 has a radioscopic image display region61 and a positional relationship display region 62. The firstradiographic image G1 which is a portion of the radiographic image setis sequentially displayed as a radioscopic image in the display region61. Therefore, the radioscopic images are displayed as a moving image inthe display region 61. In addition, the second radiographic image G2 maybe sequentially displayed as the radioscopic image in the display region61.

Here, the first positional information derivation unit 30 derives thethree-dimensional coordinates of the center position of the branch 51Bof the stent 51 as the first positional information and the secondpositional information derivation unit 33 derives the three-dimensionalcoordinates of the leading end 53A of the guide wire 53 as the secondpositional information P0. In addition, the diameter of the branch 51Bof the stent 51 is known. Therefore, the display control unit 34generates a stent image GT0 schematically indicating the shape of thebranch 51B of the stent 51 and displays the stent image GT0 in thepositional relationship display region 62. The stent image GT0 is animage as the end portion of the branch 51B of the stent 51 is viewedfrom the direction of the central axis. Further, the display controlunit 34 displays a mark M0 indicating the position of the leading end53A of the guide wire 53 in the display region 62. In this case, thedisplay control unit 34 matches the positional relationship between themark M0 and the stent image GT0 with the positional relationship betweenthe leading end 53A of the guide wire 53 and the center position of thebranch 51B of the stent 51 on the basis of the first positionalinformation and the second positional information P0. Here, the positionof the leading end 53A of the guide wire 53 is acquired inthree-dimensional coordinates. Therefore, the mark M0 indicates theposition of the leading end 53A of the guide wire 53 in the image inwhich the branch 51B of the stent 51 is viewed from the direction of thecentral axis.

The user performs an operation of inserting the guide wire 53 into thebody of the subject H while viewing the positional information screen 60such that the mark M0 is located in a circle indicating the end portionof the branch 51B in the stent image GT0. Here, the positionalrelationship between the stent image GT0 and the mark M0 illustrated inFIG. 13 indicates that the leading end 53A of the guide wire 53 isseparated from the end portion of the branch 51B of the stent 51. Whileviewing the positional information screen 60, the user can adjust theposition of the guide wire 53 inserted into the subject H such that themark M0 is located in the stent image GT0. Therefore, it is possible toreduce errors in the insertion of the guide wire 53 into the stent 51 asillustrated in FIG. 6 .

The notification unit 35 notifies that the feature point has reached thetarget point. Specifically, the notification unit 35 notifies that theguide wire 53 has reached the center position of the branch 51B of thestent 51 and has been inserted into the branch 51B through the userinterface 16. The notification may be performed by text display orsound. Further, both display and sound may be used for the notification.

Further, the sound may be changed according to the distance between theleading end 53A of the guide wire 53 and the center position of thebranch 51B. For example, a beep sound may be intermittently output asthe sound and the interval between the beep sounds may become shorter asthe leading end 53A of the guide wire 53 becomes closer to the centerposition of the branch 51B. In addition, the sound may be changed in acase in which the leading end 53A of the guide wire 53 is inserted intothe branch 51B.

In a case in which the leading end 53A of the guide wire 53 passesthrough the end portion of the branch 51B without being inserted intothe branch 51B or the distance between the leading end 53A of the guidewire 53 and the center position of the branch 51B is equal to or greaterthan a predetermined threshold value, the notification unit 35 may issuea warning indicating the fact through the user interface 16.

FIG. 14 illustrates a positional information screen in a case in whichlumbar spine fusion is performed. As illustrated in FIG. 14 , apositional information screen 70 has a radioscopic image display region71 and a positional relationship display region 72. The firstradiographic image G1 which is a portion of the radiographic image setand is obtained by capturing the image of the lumbar spine from the sideis sequentially displayed in the display region 71. Therefore, theradioscopic images are displayed as a moving image in the display region71. The first radiographic image G1 includes an image of the screw 55.Further, the second radiographic image G2 may be sequentially displayedas a radioscopic image in the display region 71.

Here, the first positional information derivation unit 30 derives thethree-dimensional coordinates of the insertion position PS and thearrival position PE of the screw 55 in the lumbar spine as the firstpositional information. The second positional information derivationunit 33 derives the three-dimensional coordinates of the leading end 55Aand the rear end 55B of the screw 55 as the second positionalinformation P0. Therefore, the display control unit 34 generates atomographic image GD0 of the lumbar spine into which the screw 55 isinserted, using the three-dimensional image of the subject H which hasbeen acquired in advance, and displays the generated tomographic imageGD0 in the positional relationship display region 72. The tomographicimage GD0 of the lumbar spine displayed in the display region 72indicates an axial cross section.

The display control unit 34 displays a mark M1 obtained by projectingthe screw 55 derived by the second positional information derivationunit 33 onto the tomographic plane of the tomographic image GD0 in thepositional relationship display region 72. In this case, the displaycontrol unit 34 matches the positional relationship between a leadingend and a rear end of the mark M1 and the insertion position PS and thearrival position PE on the tomographic image GD0 with the positionalrelationship between the leading end 55A and the rear end 55B of thescrew 55 and the insertion position PS and the arrival position PE onthe three-dimensional image on the basis of the first positionalinformation and the second positional information P0. Further, thedisplay control unit 34 displays the remaining distance from the leadingend 55A of the screw 55 derived by the second positional informationderivation unit 33 to the insertion position PS derived by the firstpositional information derivation unit 30 in an information displayregion 74 until the screw 55 reaches the insertion position PS. Thenotification unit 35 may display the information display region 74. Inthis embodiment, since the coordinate system having the insertionposition PS as the origin is also set for the radiographic images G1 andG2, it is possible to derive the distance from the current position ofthe leading end 55A of the screw 55 from the origin as the remainingdistance from the leading end 55A of the screw 55 to the insertionposition PS.

Further, the display control unit 34 derives an angle (referred to as afirst angle) of the axis of the screw 55 with respect to the axial crosssection from the positions of the leading end 55A and the rear end 55Bof the screw 55 derived by the second positional information derivationunit 33. In addition, an angle (referred to as a second angle) at whichthe screw 55 is to be inserted is derived from the insertion position PSand the arrival position PE derived by the first positional informationderivation unit 30. Then, the difference of the first angle from thesecond angle is derived and the derived angle is displayed in theinformation display region 74. In FIG. 14 , a remaining distance of 10mm and an angle of 0 degrees are displayed. The angle of 0 degreesindicates that the angle at which the screw 55 is inserted is matchedwith the angle formed by the insertion position PS and the arrivalposition PE. After the screw 55 is inserted into the lumbar spine fromthe insertion position PS, the remaining distance from the leading end55A of the screw 55 to the arrival position PE may be displayed in theinformation display region 74.

The notification unit 35 may issue a warning in a case in which theleading end 55A of the screw 55 is at a position that is separated fromthe insertion position PS by a predetermined threshold value or more.Further, in a case in which the angle of the screw 55 is greater than apredetermined threshold value (for example, 10 degrees), the displaycontrol unit 34 may issue a warning.

The user can insert the screw 55 into the body of the subject H suchthat the screw 55 is inserted into the lumbar spine from the insertionposition PS while viewing the display of the tomographic image GD0, themark M1, and the information display region 74. In addition, the usercan insert the screw 55 into the lumbar spine of the subject H such thatthe inserted screw 55 correctly reaches the arrival position PE.

Even in the case of lumbar spine fusion, the notification unit 35 maynotify that the leading end 55A of the screw 55 has reached theinsertion position PS and the leading end 55A of the screw 55 hasreached the arrival position PE through the user interface 16. Inaddition, the notification may be performed in a case in which the angleof the screw 55 is matched with the angle at which the screw 55 is to beinserted. The notification may be performed by text display or sound.Further, both display and sound may be used.

Further, the sound may be changed according to the distance between theleading end 55A of the screw 55 and the insertion position PS and thearrival position PE. For example, a beep sound may be intermittentlyoutput as the sound and the interval between the beep sounds may becomeshorter as the leading end 55A of the screw 55 becomes closer to theinsertion position PS and the arrival position PE. In addition, thesound may be changed in a case in which the leading end 55A of the screw55 reaches the insertion position PS and the arrival position PE.

Next, a process performed in this embodiment will be described. FIG. 15is a flowchart illustrating the process performed in this embodiment.First, the first positional information derivation unit 30 derives thethree-dimensional positional information of at least one target point ofa target structure in the subject H as the first positional information(Step ST1).

Then, the user inputs an imaging start command through the userinterface 16 to start the capture of the image of the subject H and theimage acquisition unit 31 acquires a set of the first radiographic imageG1 and the second radiographic image G2 (the acquisition of aradiographic image set; Step ST2). In a case in which the set of thefirst radiographic image G1 and the second radiographic image G2 isacquired, the feature point detection unit 32 detects at least onecommon feature point from the first and second radiographic images G1and G2 (Step ST3). Then, the second positional information derivationunit 33 derives the three-dimensional positional information of at leastone feature point in the subject H as the second positional information,using the positional relationship between the position of at least onefeature point detected from each of the first and second radiographicimages G1 and G2 on the detection surface 5A of the radiation detector 5and the positions of the first and second radiation sources 6A and 6B(Step ST4).

The display control unit 34 displays a positional information screen onthe user interface 16 (Step ST5). The process returns to Step ST2. Theprocess from Step ST2 to Step ST5 is repeatedly performed until aprocess end command is issued.

As such, in this embodiment, the first positional information of atleast one target point of the target structure in the subject H isderived and the three-dimensional second positional information of atleast one feature point on the insertion structure inserted to thetarget structure in the subject H is derived. Then, a positionalinformation screen indicating the positional relationship between thetarget point and the feature point is displayed on the user interface16. Therefore, it is possible to display the positional relationshipbetween the target point and the feature point with a smaller amount ofcalculation than that in a case in which the positions of the images arealigned. As a result, according to this embodiment, it is possible tounderstand the positional relationship between the target structure andthe insertion structure in the subject H in real time.

In the above-described embodiment, the first radiographic image G1 andthe second radiographic image G2 are alternately acquired. However, theinvention is not limited thereto. As illustrated in FIG. 16 , one secondradiographic image G2 may be acquired for every several frames of thefirst radiographic images G1. In FIG. 16 , the second radiographic imageG2 is acquired once while four frames of the first radiographic imagesG1 are acquired. In this case, the derivation of the positionalinformation is performed once while four frames of the firstradiographic images G1 are acquired.

In the above-described embodiment, in a case in which a cathetertreatment is performed, the first positional information derivation unit30 derives the three-dimensional coordinates of the center position ofthe branch 51B of the stent 51 as the first positional information fromthe radiographic images GE1 and GE2 or the three-dimensional image ofthe subject H. However, the invention is not limited thereto. Thefeature point detection unit 32 may detect the center position of thebranch 51B of the stent 51 as the target point from the first and secondradiographic images G1 and G2 and the first positional informationderivation unit 30 may perform the same process as the second positionalinformation derivation unit 33 to derive the three-dimensionalcoordinates of the center position of the branch 51B as the firstpositional information on the basis of the target point detected by thefeature point detection unit 32.

In the above-described embodiment, the first positional informationderivation unit 30 derives the three-dimensional positional informationof the target point of the target structure as the first positionalinformation from, for example, the radiographic images GE1 and GE2 andthe projection images GP1 and GP2 generated from and thethree-dimensional image of the subject H. However, the invention is notlimited thereto. For example, the radiographic images GE1 and GE2 may bedisplayed on the user interface 16 and the first positional informationmay be derived in response to a command to set a target point on thedisplayed images which is received from the user.

In the above-described embodiment, radiation is not particularly limitedand rays other than X-rays, such as α-rays or γ-rays, may be applied.

In the above-described embodiment, in a case in which a cathetertreatment and lumbar spine fusion are performed, the positionalinformation display device and the radiography apparatus according tothe present disclosure are applied. However, the invention is notlimited thereto. The present disclosure may be applied to any medicalprocedure using a radioscopic image.

In the above-described embodiment, the first and second radiationsources 6A and 6B are arranged in the y-axis direction illustrated inFIG. 1 in the radiation emitting unit 4. However, the first and secondradiation sources 6A and 6B may be arranged in the x-axis direction.

In the above-described embodiment, the radiation emitting unit 4includes the two radiation sources 6A and 6B. However, the invention isnot limited thereto. The radiation emitting unit 4 may include three ormore radiation sources. In this case, the positional information may bederived using a plurality of radiographic images acquired by irradiatingthe subject H with radiation emitted from three or more radiationsources. Specifically, the positional information may be derived using acombination of two radiographic images generated by radiation emittedfrom two radiation sources among three or more radiation sources.

In the above-described embodiment, for example, the following variousprocessors can be used as the hardware structure of processing unitsperforming various processes, such as the first positional informationderivation unit 30, the image acquisition unit 31, the feature pointdetection unit 32, the second positional information derivation unit 33,the display control unit 34, and the notification unit 35. The variousprocessors include a CPU which is a general-purpose processor executingsoftware (program) to function as various processing units, aprogrammable logic device (PLD), such as a field programmable gate array(FPGA), which is a processor whose circuit configuration can be changedafter manufacture, and a dedicated electric circuit, such as anapplication specific integrated circuit (ASIC), which is a processorhaving a dedicated circuit configuration designed to perform a specificprocess.

One processing unit may be configured by one of the various processorsor a combination of two or more processors of the same type or differenttypes (for example, a combination of a plurality of FPGAs or acombination of a CPU and an FPGA). In addition, a plurality ofprocessing units may be configured by one processor.

A first example of the configuration in which a plurality of processingunits are configured by one processor is an aspect in which oneprocessor is configured by a combination of one or more CPUs andsoftware and functions as a plurality of processing units. Arepresentative example of this aspect is a client computer or a servercomputer. A second example of the configuration is an aspect in which aprocessor that implements the functions of the entire system including aplurality of processing units using one integrated circuit (IC) chip isused. A representative example of this aspect is a system-on-chip (SoC).As such, various processing units are configured by using one or more ofthe various processors as a hardware structure.

In addition, specifically, an electric circuit (circuitry) obtained bycombining circuit elements, such as semiconductor elements, can be usedas the hardware structure of the various processors.

What is claimed is:
 1. A positional information display devicecomprising: at least one processor configured to: derivethree-dimensional positional information of at least one target point ofa target structure in a subject as first positional information,according to two-dimensional positional information of the at least onetarget point, based on a plurality of source image distances, whereineach of the plurality of source image distances is a distance between adetection surface of a radiation detector and each of a plurality ofradiation sources, and the radiation detector comprises a flat paneldetector comprising the detection surface, wherein the plurality ofradiation sources comprises a first radiation source and a secondradiation source, the first radiation source and the second radiationsource are arranged side by side in a first direction, and a firstradiation and a second radiation in a second direction perpendicular tothe first direction are emitted respectively from the first radiationsource and the second radiation source; derive three-dimensionalpositional information of at least one feature point on an insertionstructure inserted to the target structure in the subject as secondpositional information, according to two-dimensional positionalinformation of the at least one feature point, based on the plurality ofsource image distances; display a positional information screenindicating a positional relationship between the at least one targetpoint and the at least one feature point on a display; acquire aradiographic image set including a plurality of radiographic images,which have been generated by alternately irradiating the subject withradiation emitted from the plurality of radiation sources provided atdifferent positions and alternately detecting the radiation transmittedthrough the subject using the radiation detector, at a predeterminedtime interval, wherein the different positions comprises a firstradiation source position of the first radiation source and a secondradiation source position of the second radiation source; detect the atleast one feature point on the insertion structure inserted to thetarget structure in the subject from each of the plurality ofradiographic images included in the radiographic image set; and derivethe second positional information using a positional relationshipbetween a position of the at least one feature point detected from eachof the plurality of radiographic images on the detection surface of theradiation detector and positions of the plurality of radiation sources.2. The positional information display device according to claim 1,wherein the at least one processor further is configured to display thepositional information screen including a radiographic image displayregion in which some of the plurality of radiographic images aredisplayed and a positional relationship display region in which thepositional relationship is displayed on the display.
 3. The positionalinformation display device according to claim 1, wherein the at leastone processor further is configured to provide a display signal or asound signal that the at least one feature point has reached the atleast one target point.
 4. The positional information display deviceaccording to claim 3, wherein the at least one processor further isconfigured to issue a warning in a case in which the at least onefeature point deviates from the at least one target point by apredetermined distance or a predetermined angle.
 5. The positionalinformation display device according to claim 1, wherein the insertionstructure is a surgical instrument that is inserted into the subject. 6.The positional information display device according to claim 1, whereinthe target structure is a stent that is inserted into a blood vessel ofthe subject, the at least one target point is a center position of anend portion of the stent, the insertion structure is a guide wire forexpanding the stent, and the at least one feature point is a leading endof the guide wire.
 7. The positional information display deviceaccording to claim 1, wherein the target structure is a lumbar spine ofthe subject, the at least one target point is at least one of aninsertion position or an arrival position of a screw that is insertedinto the lumbar spine, the insertion structure is the screw, and the atleast one feature point is at least one of a leading end or a rear endof the screw.
 8. A radiography apparatus comprising: a plurality ofradiation sources that are provided at a predetermined interval; apositional information display device according to claim 1; a radiationdetector configured to be arranged towards the plurality of radiationsources, the radiation detector being configured to detect radiation,which has been emitted from each of the plurality of radiation sourcesand transmitted through a subject to generate a radiographic image ofthe subject; and at least one processor configured to generate aradiographic image set including a plurality of radiographic images at apredetermined time interval by controlling a time point when each of theplurality of radiation sources emits the radiation and a time point whenthe radiation detector detects the radiation transmitted through thesubject such that the plurality of radiation sources alternatelyirradiate the subject with the radiation and the radiation detectoralternately detects the radiation transmitted through the subject. 9.The radiography apparatus according to claim 8, wherein the plurality ofradiation sources comprises two radiation sources.
 10. The radiographyapparatus according to claim 9, wherein the at least one processor isfurther configured to: direct one of the two radiation sources tosequentially emit radiation at a first time interval, direct the otherradiation source to sequentially emit radiation at a second timeinterval equal to or longer than the first time interval, and controlthe radiation detector so as to detect the radiation at all time pointswhen the two radiation sources emit the radiation, and acquire, as theradiographic image set, two radiographic images generated by detectingtwo temporally adjacent radiation using the radiation detector, the twotemporally adjacent radiation having been emitted from the two radiationsources.
 11. A positional information display method comprising:deriving three-dimensional positional information of at least one targetpoint of a target structure in a subject as first positionalinformation, according to two-dimensional positional information of theat least one target point, based on a plurality of source imagedistances, wherein each of the plurality of source image distances is adistance between a detection surface of a radiation detector and each ofa plurality of radiation sources, and the radiation detector comprises aflat panel detector comprising the detection surface, wherein theplurality of radiation sources comprises a first radiation source and asecond radiation source, the first radiation source and the secondradiation are arranged side by side in a first direction, and a firstradiation and a second radiation in a second direction perpendicular tothe first direction are emitted respectively from the first radiationsource and the second radiation source; deriving three-dimensionalpositional information of at least one feature point on an insertionstructure inserted to the target structure in the subject as secondpositional information, according to two-dimensional positionalinformation of the at least one feature point, based on the plurality ofsource image distances; displaying a positional information screenindicating a positional relationship between the at least one targetpoint and the at least one feature point on a display; acquiring aradiographic image set including a plurality of radiographic images,which have been generated by alternately irradiating the subject withradiation emitted from the plurality of radiation sources provided atdifferent positions and alternately detecting the radiation transmittedthrough the subject using the radiation detector, at a predeterminedtime interval, wherein the different positions comprises a firstradiation source position of the first radiation source and a secondradiation source position of the second radiation source; detecting theat least one feature point on the insertion structure inserted to thetarget structure in the subject from each of the plurality ofradiographic images included in the radiographic image set; and derivingthe second positional information using a positional relationshipbetween a position of the at least one feature point detected from eachof the plurality of radiographic images on the detection surface of theradiation detector and positions of the plurality of radiation sources.12. A non-transitory computer-readable storage medium that stores apositional information display program that causes a computer toperform: a step of deriving three-dimensional positional information ofat least one target point of a target structure in a subject as firstpositional information, according to two-dimensional positionalinformation of the at least one target point, based on a plurality ofsource image distances, wherein each of the plurality of source imagedistances is a distance between a detection surface of a radiationdetector and each of a plurality of radiation sources, and the radiationdetector comprises a flat panel detector comprising the detectionsurface, wherein the plurality of radiation sources comprises a firstradiation source and a second radiation source, the first radiationsource and the second radiation source are arranged side by side in afirst direction, and a first radiation and a second radiation in asecond direction perpendicular to the first direction are emittedrespectively from the first radiation source and the second radiationsource; a step of deriving three-dimensional positional information ofat least one feature point on an insertion structure inserted to thetarget structure in the subject as second positional information,according to two-dimensional positional information of the at least onefeature point, based on the plurality of source image distances; a stepof displaying a positional information screen indicating a positionalrelationship between the at least one target point and the at least onefeature point on a display; a step of acquiring a radiographic image setincluding a plurality of radiographic images, which have been generatedby alternately irradiating the subject with radiation emitted from theplurality of radiation sources provided at different positions andalternately detecting the radiation transmitted through the subjectusing the radiation detector, at a predetermined time interval, whereinthe different positions comprises a first radiation source position ofthe first radiation source and a second radiation source position of thesecond radiation source; a step of detecting the at least one featurepoint on the insertion structure inserted to the target structure in thesubject from each of the plurality of radiographic images included inthe radiographic image set; and, a step of deriving the secondpositional information using a positional relationship between aposition of the at least one feature point detected from each of theplurality of radiographic images on the detection surface of theradiation detector and positions of the plurality of radiation sources.13. A positional information display device comprising: at least oneprocessor configured to: derive three-dimensional positional informationof at least one target point of a target structure in a subject as firstpositional information; acquire a radiographic image set including aplurality of radiographic images, which have been generated byalternately irradiating the subject with radiation emitted from aplurality of radiation sources provided at different positions andalternately detecting the radiation transmitted through the subjectusing a radiation detector, at a predetermined time interval; detect atleast one feature point on an insertion structure inserted to the targetstructure in the subject from each of the plurality of radiographicimages included in the radiographic image set by using a learned model,which has been trained so as to detect the at least one feature pointfrom the plurality of radiographic images; derive, as second positionalinformation, three-dimensional positional information of the at leastone feature point using a positional relationship between a position ofthe at least one feature point detected from each of the plurality ofradiographic images on a detection surface of the radiation detector andpositions of the plurality of radiation sources; and display apositional information screen indicating a positional relationshipbetween the at least one target point and the at least one feature pointon a display.
 14. The positional information display device according toclaim 13, wherein the processor further configured to: display thepositional information screen including a radiographic image displayregion in which some of the plurality of radiographic images aredisplayed and a positional relationship display region in which thepositional relationship is displayed on the display.
 15. The positionalinformation display device according to claim 13, wherein the processorfurther configured to: notify that the at least one feature point hasreached the at least one target point.
 16. The positional informationdisplay device according to claim 15, wherein the processor furtherconfigured to: issue a warning in a case in which the at least onefeature point deviates from the at least one target point by apredetermined distance or a predetermined angle.
 17. The positionalinformation display device according to claim 13, wherein the insertionstructure is a surgical instrument that is inserted into the subject.18. The positional information display device according to claim 13,wherein the target structure is a stent that is inserted into a bloodvessel of the subject, the at least one target point is a centerposition of an end portion of the stent, the insertion structure is aguide wire for expanding the stent, and the at least one feature pointis a leading end of the guide wire.
 19. The positional informationdisplay device according to claim 13, wherein the target structure is alumbar spine of the subject, the at least one target point is at leastone of an insertion position or an arrival position of a screw that isinserted into the lumbar spine, the insertion structure is the screw,and the at least one feature point is at least one of a leading end or arear end of the screw.
 20. A radiography apparatus comprising: aplurality of radiation sources that are provided at a predeterminedinterval; a positional information display device according to claim 14;and a radiation detector configured to be arranged towards the pluralityof radiation sources, the radiation detector being configured to detectradiation, which has been emitted from each of the plurality ofradiation sources and transmitted through a subject to generate aradiographic image of the subject, and at least one processor configuredto generate a radiographic image set including a plurality ofradiographic images at a predetermined time interval by controlling atime point when each of the plurality of radiation sources emits theradiation and a time point when the radiation detector detects theradiation transmitted through the subject such that the plurality ofradiation sources alternately irradiate the subject with the radiationand the radiation detector alternately detects the radiation transmittedthrough the subject.
 21. The radiography apparatus according to claim20, wherein the plurality of the radiation sources comprises tworadiation sources.
 22. The radiography apparatus according to claim 21,wherein the at least one processor is further configured to: direct oneof the two radiation sources to sequentially emit radiation at a firsttime interval, direct the other radiation source to sequentially emitradiation at a second time interval equal to or longer than the firsttime interval, and control the radiation detector so as to detect theradiation at all time points when the two radiation sources emit theradiation, and acquire, as the radiographic image set, two radiographicimages generated by detecting two temporally adjacent radiation usingthe radiation detector, the two temporally adjacent radiation havingbeen emitted from the two radiation sources.